1. Field of Invention
The present invention relates a turbo-charger having an anti-surge valve circulating reversed air to an upstream side of a compressor when a throttle valve is closed.
2. Description of Related Art
A gasoline engine uses a throttle valve to control intake air, and the intake air can flow backwards at a point of a tip-out (a behavior of taking a driver's foot off the accelerator).
Particularly, in a case that a turbo-charger is mounted therein, the reversed intake air collides with a blade of a compressor to generate noise and vibration and to deteriorate the durability thereof.
A bypass line is formed between an upstream side and a downstream side of the compressor, and an anti-surge valve is disposed on the bypass line so as to resolve the above problem.
The anti-surge valve opens the bypass line to re-circulate the air between the throttle valve and the compressor so as to reduce the noise and vibration generated from the blade of the compressor.
FIG. 1 is a schematic diagram of an intake system of an engine. Referring to the drawing, the intake system of the engine includes a intake line 100, a compressor 110a, an anti surge valve 120, an intercooler pipe 130, an intercooler 140, a throttle valve 145, an intake manifold 150, and an exhaust line 160, and a turbine 110b. 
Meanwhile, a turbulent flow is formed in air that re-circulates to the intake line as an inlet of the compressor through the anti surge valve by a tip-out behavior and the air collides with the blade of the compressor that rotates at a high speed to generate high pitched tone noise by pulsation.
Further, during the tip-out behavior, the air does not flow uniformly the anti-surge valve such that flow separation phenomenon is formed and noise is formed by a turbulent flow.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.